The author tries to reconstruct and analyze the acts of sabotage carried out in Poland by the German intelligence from March to August 1939. The fact that there was German diversion in Poland was held back from the world public opinion. Its existence is, however, confirmed by documents of the Polish Government Police, the Polish counterintelligence, the German intelligence service and the German secret service preserved in Polish and German archives. Both, the intelligence and the secret service planned those acts of sabotage in detail. An example of their activity is the series of assaults on German property situated in either Polish or German territory performed in August 1939. The sabotage organization created by the Wroclaw Abwehra at the end of July 1939 numbered around 10 800 collaborators (6800 Germans and 4000 Ukrainians). They were particularly active in Silesia and the provinces of Great Poland (Wielkopolska) and Little Poland (Malopolska).